The present invention relates to a haymaking machine for the tedding and windrowing of fodder, comprising one or more rake wheels driven in rotation. The said rake wheels are provided with arms carrying working tools which are mounted for pivoting in support bearings and have at their end towards the rotation axis of the corresponding rake wheel a control crank provided with a roller which moves in a guide cam so as to pivot the working tools, over a partial range of their path of revolution, upwards and in the direction opposite to the direction of rotation of the corresponding rake wheel during windrowing.
Machines based upon this principle carry out excellent windrowing work.
For tedding it is desirable to be able to attenuate or neutralise the pivoting movement of the working tools in order to obtain vigorous treatment of the fodder.
On a machine of this kind it is known to withdraw the rollers, fixed to the tool carrier arms, from the guide cam by displacement of the said rollers outwards for tedding and to return the rollers into contact with the said cam by inward displacement of the said rollers for windrowing. This transposition of the tool-carrier arms from the tedding position into the windrowing position and vice versa necessitates delicate adjustments.
Moreover each of the tool-carrier arms must be brought separately into the tedding position and immobilised in this position so that it can no more rotate about its longitudinal axis, which frequently represents a loss of time for the user.
Furthermore this machine does not permit of having a substantial increase in the diameter of the trajectories described by the working tools in tedding, which on a machine having two rake wheels necessitates the use of a telescopic frame to reduce the spacing between the trajectories described by the working tools of two adjacent rake wheels, if it is desired to obtain effective tedding work.
On another known machine of this kind the rollers fast with the tool-carrier arms are applied against a guide cam by means of torsion springs. On this machine the tool-carrier arms of one and the same rake wheel can be brought from the windrowing position into the tedding position by a downward disengagement of the guide cam until the rollers of the tool-carrier arms are out of engagement with the said cam.
A great drawback of this form of embodiment resides in the fact that in the transposition of the machine into the windrowing position or into the tedding position it is necessary for the guide cam to be displaced axially, which is not desirable in view of the fact that the position of the said cam and its rigidity in relation to its support axis determine the trajectory described by the working tools during windrowing, and thus the quality of the windrowing work. Moreover there is no increase in the diameter of the trajectories described by the working tools in the transposition from the windrowing position into the tedding position, which is detrimental to the quality of the tedding work on a machine having two rake wheels. In addition the working tools do not extend substantially perpendicularly to the ground, in front of their rake wheels -- seen in the direction of travel -- in the tedding position, which at the same time prevents good grasping of the fodder in front of the rake wheel and good clearance of the said fodder behind the rake wheel. Furthermore the torsion springs which apply the rollers against the guide cam are continually bent during work, resulting in rapid fatigue of the said springs followed by an appreciable reduction of the quality of work, in particular during tedding when the fodder to be displaced is green and thus heavy.
On a final machine of the kind concerned by the invention the rollers fast with the tool-carrier arms move on a guide cam of modifiable profile. It is not desirable to interfere with the cam for the transposition from the windrowing position into the tedding position or vice versa, in view of the fact that the rigidity of the cam determines the quality of work. Moreover it is difficult, from the design viewpoint, to produce a guide cam with variable profile. Furthermore on this machine there is no increase of the diameter of the trajectories described by the working tools during transposition into the tedding position.
Finally the said working tools do not extend substantially perpendicularly to the ground, in front of their rake wheels, in the said tedding position.
The purpose of the present invention consists in obtaining a haymaking machine of the kind described in the introduction which does not possess the above-mentioned drawbacks of the known machines.